Have you decided to install solar PV yet? You want to reduce costs, become more energy independent and reduce your carbon footprint. You have determined that there is an available roof space, site or parking area (i.e. solar canopy) that can be used to host your solar net metering system. Now you need to determine the right size for your solar system. This article will guide you through the most important considerations when determining how to design a properly sized solar system to optimize your investment.
1. What is your total annual electricity use?
In many countries, self-generation is achieved through net metering or net billing. You can learn more about net metering here. While net metering or net billing rules may vary slightly across the country, in general, they allow you to produce as much electricity as you consume each year. Net metering and net billing policies are designed to allow you to offset your own electricity usage, rather than produce more electricity than you use. If you produce more solar energy than you use in a year, you’ll usually give the excess power to the utility for free! Therefore, it is important to properly size your solar system.
This means that the first step in determining the maximum size of your solar net metering system is to know how much electricity you consume each year. Therefore, you will need to perform a billing analysis to determine the total amount of electricity (in kilowatt hours) your business consumes. Whatever you consume each year will be the maximum amount of electricity your solar system will need to produce. Determining how much power your system produces depends on the availability of space and the projected output of your solar system.
2. How much space is available in your solar system?
Solar panel technology has advanced by leaps and bounds over the last 20 years and continues to improve. This means that solar panels have not only become cheaper, but also more efficient. Today, you can now install more solar panels and generate more solar energy from the same area than 5 years ago.
Leading national companies have completed hundreds of solar designs for different building types. Based on this experience, we have developed solar sizing guidelines based on different building types. However, because there are some differences between the overall efficiency of solar panels, the space guidelines below may vary depending on the type of solar panel used.
If you are installing solar on a retail store or school property, you will see more roof obstructions, such as heating, ventilation and air conditioning (HVAC) units, as well as gas lines and other items that require setbacks for regular maintenance. Industrial or commercial properties typically have fewer rooftop obstructions, so there is more space available for solar panels.
Based on our experience in solar system design, we have calculated the following general rules to estimate the amount of solar energy you can plan to install. You can use these guidelines to get an approximate system size (in kWdc) based on the square footage of the building.
Industrial: +/-140 Square feet/kWdc
3. How much power will your system generate?
As we mentioned in Part I, net metering systems are designed to generate as much electricity as you consume in a year, and any generation you generate is typically provided to the utility company at no cost. Therefore, right-sizing your system is important to avoid spending money on solar that is less valuable to you and to make the most of your investment.
Enter solar design software such as Helioscope or PVSyst.These allow us to determine how much electricity your solar system will produce based on the location-specific features of your building or site or parking lot.
There are a variety of factors that can affect solar production, including the tilt of the panels, whether they are located due south (i.e. azimuth), whether there is near or distant shading, what the summer and winter/snow related dirt will be, and the losses throughout the system, such as in the inverter or wiring.
4. Plan Properly
Only by performing a billing analysis and preliminary system design and production estimates will you know if your solar system is right for your business or application. Again, this is important, so you don’t oversize your system relative to your annual demand and make your solar available to the utility company. However, with some feasibility work and planning, you can rest assured that your investment in solar will be customized to your needs.